The system of the present invention provides for the first time the ability to track an intruder after he has crossed a perimeter boundary. It uses a grid of leaky coaxial cables as sensors and provides location information by identifying the specific subboundary within the grid which was crossed with a coincidence location logic circuit. The system further provides a method of detecting and locating an intrusion not only across a perimeter boundary, but also within the boundary. No system now exists to track an intruder within the zone perimeter. It is noted this system can be used to provide a high level of security for a number of applications and installations such as aircraft parking ramps, material storage areas, and missile launch complexes, etc.